With the miniaturization of semiconductor devices, the exposure light of the exposure apparatus used to manufacture semiconductor devices has been shifted to shorter wavelengths. For example, there are expectations for practical application of the exposure technique using extreme ultraviolet (EUV) light having a wavelength of 13.5 nanometers (nm). In such exposure using EUV light, transmissive lenses cannot be used because of the high absorption coefficient of the substance. Instead, a reflective optical system using mirrors is used. Thus, in exposure using EUV light, a reflection type photomask is used.
The development of a special technology for evaluating the performance of an exposure apparatus using a reflection type photomask is necessary.